Integrating Dual-Metal Sites into Covalent Organic Frameworks for Enhanced Photocatalytic CO2 Reduction

Abstract

Photocatalytic CO2 reduction holds great promise for synchronously addressing carbon neutrality and producing fuels, although enhancing the photocatalyst activity and tuning the product selectivity remain enormous challenges. Herein, we synthesized four crystalline and porous benzothiadiazole-based covalent organic frameworks (COFs) with different carbonyl groups and reported a dual metalation strategy to fabricate Co and Ni dual-metal sites anchored on the benzothiadiazole-based COFs by the interaction between metal and thiadiazole for high-performance CO2 photoreduction. Among the as-synthesized COFs metalated by Co/Ni dual sites, CoNi–COF-3 achieved an impressive CO generation rate of 2567 μmol g–1 h–1 with a selectivity of 92.2%, which were significantly higher than those of single sites. Experimental and theoretical results revealed that the superior photocatalytic performance was attributed to the synergic effect of the fully β-ketoenamine-tautomerized COF-3 configuration and dual-metal sites, which not only facilitated the photogenerated charge carrier dynamics but also reduced the energy barriers of *COOH formation and promoted CO2 adsorption and CO desorption. This work provides valuable insights into the future design of improved COF photocatalysts for high-performance CO2 conversion.